The present disclosure herein relates to a lithium rechargeable battery, and more particularly, to a lithium rechargeable battery for self-charging with an energy harvesting device.
Energy harvesting devices in general employ a principle of converting energy present in the environment, such as light, heat, vibration/pressure, radio wave, etc., into electric energy. Typical Energy harvesting devices include photovoltaic cells which directly convert light into electricity by the photoelectric effect, piezoelectric devices which convert vibration or pressure into electricity by the piezoelectric effect, and thermoelectric devices which directly transform heat into electricity by the thermoelectric effect. However, it is substantially impossible to generate a stable output over a long period of time due to spatial and environmental restrictions of the energy sources including light, heat, vibration/pressure, radio wave, etc. Since the voltage generated from a single energy harvesting device is usually one volt or lower, a series connection or modularization must be required when these devices are applied to other devices. Moreover, when the supply of the surrounding energy is interrupted for an extended period, devices into which the energy harvesting devices are applied may stop being driven.
Recently, studies on connecting a rechargeable battery which is an energy reservoir into an energy harvesting device have been actively conducted to overcome these drawbacks. That is, the development of self-charge power modules has been attempted, which ensures that the whole electric energy generated by an energy harvesting device is charged into a rechargeable battery in real time and the energy stored in the rechargeable battery is stably provided to another device. However, since energy generation by an energy harvesting device is basically irregular and the output is neither steady nor stable, the safe storage of the generated energy into a rechargeable battery has become an increasingly important issue.
Self-charging power modules may replace typical primary batteries applied to sensor nodes. Especially, the self-charging power modules are advantageously applied to the independent power supply devices installed in the environment incapable of wired charging and easy replacement of batteries. Accordingly, durability and safety are critical considerations for the rechargeable batteries applied to self-charging power modules. Rechargeable batteries applied to self-charging power modules should be able to be charged at a high speed such that they may be easily applied under the irregular charging environment, have a high charging efficiency, and be a reliable and long life span battery to secure cycle stability and cell safety.